The present invention generally relates to lockable syringes for pressurizing medical devices, such as balloon catheters, as well as to methods of assembling lockable syringes.
During inflation of a balloon catheter, it is desirable for the medical provider to be able to easily and precisely control the pressure which is provided to the balloon. While it is desirable to be able to quickly apply or remove a substantial amount of pressure to or from the balloon, it is also desirable to be able to add just a little more pressure or remove just a little pressure from the balloon.
Lockable syringes (see, for example, the devices disclosed in U.S. Pat. Nos. 5,057,078 and 6,938,319) have become common in the medical field for precisely controlling the pressure which is applied to a balloon catheter. A typical lockable syringe provides that, in one state, a plunger is movable quickly into or out of a barrel, merely by pulling on a handle of the plunger. This causes a quick change in pressure with regard to the balloon catheter. On the other hand, the syringe can be placed in the locked position, thereby putting it in another state. In this other state, the handle of the plunger cannot be pushed or pulled. Instead, the handle must be rotated, thereby causing the plunger to slowly advance into or retract from the barrel. As such, the lockable syringe provides operation in effectively two states—a first state for macro movements, during which state the balloon catheter pressure can be changed greatly relatively quickly; and a second state for micro movements, during which state the balloon catheter pressure can be more precisely and slowly controlled.
While lockable syringes provide several advantages, many lockable syringes which are currently available for use in a balloon catheter procedure are difficult to use, difficult to assemble, and/or include too many parts.